Download Principles of Management of Impacted teeth

Principles of Management of
Impacted teeth
Larry J. Peterson
CHAPTER
CHAPTER OUTLINE
INDICATIONS FOR REMOVAL OF IMPACTED TEETH
Prevention of Periodontal Disease
Prevention of Dental Caries
Prevention of Pericoronitis
Prevention of Root Resorption
Impacted Teeth under a Dental Prosthesis
Prevention of Odontogenic Cysts and Tumors
Treatment of Pain of Unexplained Origin
Prevention of Fracture of the Jaw
Facilitation of Orthodontic Treatment
Optimal Periodontal Healing
CONTRAINDICATIONS FOR REMOVAL OF IMPACTED
TEETH
Extremes of Age
Compromised Medical Status
Probable Excessive Damage to Adjacent Structures
Summary
CLASSIFICATION SYSTEMS OF IMPACTED TEETH
Angulation
Relationship to Anterior Border of Ramus
Relationship to Occlusal Plane
Summary ROOT
MORPHOLOGY
Size of Follicular Sac
Density of Surrounding Bone
Contact with Mandibular Second Molar
Relationship to Inferior Alveolar Nerve
Nature of Overlying Tissue MODIFICATION OF
CLASSIFICATION SYSTEMS FOR
MAXILLARY IMPACTED TEETH
DIFFICULTY OF REMOVAL OF OTHER IMPACTED TEETH
SURGICAL PROCEDURE PERIOPERATIVE PATIENT
MANAGEMENT
n impacted tooth is one that fails to erupt into the
dental arch within the expected time. The tooth
becomes impacted because adjacent
teeth, dense overlying bone, or excessive soft tissue prevents
eruption. Because impacted teeth do not erupt, they are
retained for the patient's lifetime unless surgically removed. The
term unerupted includes both impacted teeth and teeth that
are in the process of erupting. The term embedded is
occasionally used interchangeably with the term impacted.
Teeth most often become impacted because of inadequate
dental arch length and space in which to erupt; that is, the
total length of the alveolar bone arch is smaller than the total
length of the tooth arch. The most common impacted teeth
are the maxillary and mandibular third molars, followed by
the maxillary canines and mandibular premolars. The third
molars are the most frequently impacted, because they are
the last teeth to erupt; therefore they are the most likely to
have inadequate space for eruption.
184
In the anterior maxilla, the canine tooth is also commonly prevented from erupting by crowding from other
teeth. The canine tooth usually erupts after the
maxillary lateral incisor and maxillary first premolar. If
space is inadequate to allow eruption, the canine tooth
becomes impacted. In the anterior mandible a similar
situation affects the mandibular premolars, because
they erupt after the mandibular first molar and
mandibular canine. Therefore if room for eruption is
inadequate, one of the premolars, usually the second
premolar, remains un-erupted and becomes impacted.
As a general rule, all impacted teeth should be removed unless removal is contraindicated. Extraction
should be performed as soon as the dentist determines
that the tooth is impacted. Removal of impacted teeth
becomes more difficult with advancing age. The dentist
should not recommend that impacted teeth be left in
place until they cause difficulty. If the tooth is left in
place until problems arise, the patient may experience an
increased incidence of local tissue morbidity, loss of adjacent teeth and bone, and potential injury to adjacent
vital structures. Additionally, if removal of impacted
teeth is deferred until they cause problems later in life,
surgery is more likely to be complicated and hazardous,
because the patient may have compromising systemic
diseases. A fundamental precept of the philosophy of
dentistry is that problems should be prevented. Preventive dentistry dictates that impacted teeth are to be
removed before complications arise.
This chapter discusses the management of impacted
teeth, It is not a thorough or in-depth discussion of the
technical aspects of surgical impaction removal. Instead
its goal is to provide both the information necessary for
proper management and a basis for determining the difficulty of surgery.
INDICATIONS FOR REMOVAL OF IMPACTED TEETH
OF IMPACTED TEETH ___
All impacted teeth should be considered for removal as
soon as the diagnosis is made. The average age for completion of the eruption of the third molar is age 20,
although eruption may continue in some patients until
age 25. During normal development the lower third
molar begins its development in a horizontal angulation,
and as the tooth develops and the jaw grows, the angulation changes from horizontal to mesioangular to vertical.
Failure of rotation from the mesioangular to the vertical
direction is the most common cause of the tooth
remaining impacted. The second major factor is that
the mesiodistal dimension of the teeth versus the
length of the jaw is such that inadequate room exists in
the alveolar process anterior to the anterior border of the
ramus to allow the tooth to erupt into position.
As noted earlier, some third molars will continue to
erupt after age 20, coming into final position by age 25.
Multiple factors are associated with continued eruption.
When late eruption occurs, the unerupted tooth is usually covered only with soft tissue or very slightly with
bone. These teeth are almost always in a vertical
position
and are relatively superficially positioned with respect to
the occlusal plane of the adjacent second molar.
Finally and perhaps most importantly, sufficient space
exists between the anterior border of the ramus and the
second molar tooth to allow eruption.1-2 Likewise, if the
tooth does not erupt after age 20, it is most likely covered
with bone. In addition, the tooth is likely a mesioangular
impaction and located lower in the alveolar process near
the cervical level of the adjacent second molar. Finally,
inadequate space exists to allow eruption. Therefore the
dentist and surgeon can use these parameters to predict
whether or not a tooth will erupt into the arch or remain
impacted.
Early removal reduces the postoperative morbidity and
allows for the best healing.3-6 Younger patients tolerate the
procedure better and recover more quickly and with less
interference to their daily lives. Periodontal healing is
better in the younger patient, because of better and more
complete regeneration of the periodontal tissues. Moreover, the procedure is easier to perform in younger
patients. The ideal time for removal of impacted third
molars is when the roots of the teeth are one-third
formed and before they are two-thirds formed, usually
during the late teenage years, between ages 17 and 20.
If impacted teeth are left in the alveolar process, it is
highly probable that one or more of several problems will
result.7-8 To prevent this, impacted teeth should be
removed.
Prevention of Periodontal Disease
Erupted teeth adjacent to impacted teeth are predisposed
to periodontal disease (Figs. 9-1 and 9-2). The mere presence of an impacted mandibular third molar decreases
the amount of bone on the distal aspect of an adjacent
second molar (see Fig. 9-1). Because the most difficult
tooth surface to keep clean is the distal aspect of the last
tooth in the arch, the patient may have gingival inflammation with apical migration of the gingival attachment
on the distal aspect of the second molar. With even
minor gingivitis the causative bacteria have access to a
large portion of the root surface, which results in the
early formation of severe periodontitis (see Fig. 9-2).
Patients with impacted mandibular third molars often
have deep periodontal pockets on the distal aspect of the
second molars but have normal sulcular depth in the
remainder of the mouth.
The accelerated periodontal problem resulting from an
impacted third molar is especially serious in the maxilla.
As a periodontal pocket expands apically, it becomes
involved with the distal furcation of the maxillary second
molar relatively early, which makes advancement of the
periodontal disease more rapid and severe. In addition,
treatment of the localized periodontal disease around the
maxillary second molar is more difficult because of the
distal furcation involvement.
By removing the impacted third molars early, periodontal disease can be prevented and the likelihood of
bony healing and bone fill into the area previously occupied by the crown of the third molar is increased.4-6
FIG. 9-1 Radiograph of mandibular third molar impacted against second molar, with bone loss
resulting from presence of third molar.
FIG. 9-2 Radiographs show variations of mandibular third molar impacted against second molar,
with severe bone loss secondary to periodontal disease and third molar.
Prevention of Dental Caries
Prevention of Pericoronitis
When a third molar is impacted or partially impacted, the
bacteria that cause dental caries can be exposed to the
distal aspect of the second molar, as well as to the third
molar. Even in situations in which no obvious
communication between the mouth and the impacted third
molar exists, there may be enough communication to
allow for caries production (Figs. 9-3 through 9-5).
When a tooth is partially impacted with a large amount of
soft tissue over the axial and occlusal surfaces, the patient
frequently has one or more episodes of pericoro-nitis.9
Pericoronitis is an infection of the soft tissue around the
crown of a partially impacted tooth and is caused by the
normal oral flora. For most patients the bacteria and host
defenses maintain a delicate balance, but host defenses
cannot eliminate the bacteria.
FIG. 9-3 Radiograph of caries in mandibuiar second molar secondary to presence of impacted
third molar.
If the host defenses are compromised (e.g., during minor
illnesses, such as influenza or an upper respiratory infection, or from severe fatigue), infection can occur. Thus
although the impacted tooth has been present for some
time without infection, if the patient experiences a mild,
transient decrease in host defenses, pericoronitis may result.
Pericoronitis can also arise secondary to minor trauma
from a maxillary third molar. The soft tissue that covers the
occlusal surface of the partially erupted mandibular third
molar (known as the operculum) can be traumatized and
become swollen. Often the maxillary third molar further
traumatizes the already swollen operculum, which causes
increased swelling that again can be traumatized more easily. This spiraling cycle of trauma and swelling is often
interrupted only by removal of the maxillary third molar.
Another common cause of pericoronitis is entrapment
of food under the operculum. During eating, a small
amount of food may be packed into the pocket between
the operculum and the impacted tooth. Because this
pocket cannot be cleaned, bacteria invade it and pericoronitis begins.
Streptococci and a large variety of anaerobic bacteria
(the usual bacteria that inhabit the gingival sulcus) cause
pericoronitis. It can be treated initially by mechanically
debriding the large periodontal pocket that exists under
the operculum by using hydrogen peroxide as an irrigating solution. Hydrogen peroxide not only mechanically
removes bacteria with its foaming action, it also reduces
the number of anaerobic bacteria by releasing oxygen
into the usually anaerobic environment of the oral cavity. Other irrigates, such as chlorhexidine or iodophors,
can reduce the bacterial population of the pocket.
Pericoronitis can present as a very mild infection or
as a severe infection that requires hospitalization of the
patient. Just as the severity of the infection varies,
the
FIG. 9-4 Radiograph of caries in mandibular impacted molar.
treatment and management of this problem vary from
very mild to aggressive.
In its mildest form, pericoronitis is a localized tissue
swelling and soreness. For patients with a mild infection,
irrigation and curettage by the dentist and home irrigations by the patient usually suffice.
If the infection is slightly more severe with a large
amount of local soft tissue swelling that is traumatized by a
maxillary third molar, the dentist should consider extracting the maxillary third molar in addition to local irrigation.
FIG. 9-5 Radiograph of caries in both impacted third molar and second molar.
For patients who have (in addition to local swelling
and pain) mild facial swelling, mild trismus secondary
to inflammation extending into the muscles of
mastication, and a low-grade fever, the dentist should
consider administering an antibiotic along with
irrigation and extraction. The antibiotic of choice is
penicillin.
Pericoronitis can lead to serious fascial space
infections. Because the infection begins in the posterior
mouth, it can spread rapidly into the fascial spaces of
the mandibular ramus and the lateral neck. If a patient
develops trismus (with an inability to open the mouth
more than 20 mm), a temperature of greater than 101° F,
facial swelling, pain, and malaise, the patient should be
referred to an oral and maxillofacial surgeon, who may
admit the patient to the hospital.
Patients who have had one episode of pericoronitis,
although managed successfully by these methods, will
continue to have episodes of pericoronitis, unless the
offending mandibular third molar is removed. The
patient should be informed that the tooth should be
removed at the earliest possible time to prevent
recurrent infections. The mandibular third molar
should not be removed until the signs and symptoms
of pericoronitis have been completely resolved. The
incidence of postoperative complications, specifically
dry socket and postoperative infection, increases if the
tooth is removed during the time of active infection.
Prevention of pericoronitis can be achieved by
removing the impacted third molars before they
penetrate the oral mucosa and are visible. Although
excision of the surrounding soft tissue, or
operculectomy, has been advocated as a method for
preventing pericoronitis without removal of the
impacted tooth, it is very painful and usually does not
work. The soft tissue excess tends to recur, because it
drapes over the impacted tooth and causes regrowth of
the operculum. The overwhelming majority of cases of
pericoronitis can be prevented only by extraction of the
tooth.
Prevention of Root Resorption
Occasionally, an impacted tooth causes sufficient pressure
on the root of an adjacent tooth to cause root resorp-tion
(Figs. 9-6 and 9-7). Although the process by which root
resorption occurs is not well defined, it appears to be
similar to the resorption process primary teeth undergo
in the presence of the succedaneous teeth. Removal of
the impacted tooth may result in salvage of the adjacent
tooth by cemental repair. Endodontic therapy may be
required to save these teeth.
Impacted Teeth under a Dental Prosthesis
When a patient has an edentulous area restored, there are
several reasons that impacted teeth in the area should be
removed before the prosthetic appliance is constructed.
After teeth are extracted, the alveolar process slowly
undergoes resorption. Thus the impacted tooth becomes
closer to the surface of the bone, giving the appearance of
erupting. The denture may compress the soft tissue on
the impacted tooth, which is no longer covered with
bone; the result is ulceration of the overlying soft tissue
and initiation of an odontogenic infection (Fig. 9-8).
Impacted teeth should be removed before prosthesis is
constructed because, if the impacted tooth must be
removed after construction, the alveolar ridge may be so
altered by the extraction that the prosthesis becomes
unattractive and less functional (Fig. 9-9). In addition, if
removal of impacted teeth in edentulous areas is
achieved before the prosthesis is made, the patient is
probably in good physical condition. Waiting until the
overlying bone has resorbed and ulceration with infection
occurs does not produce a favorable situation for
extraction. If extraction is postponed, the patient will be
older and more likely to be in poorer health. Furthermore, the mandible may have become atrophic, which
increases the likelihood of fracture during tooth removal
(Fig. 9-10).
FIG. 9-6 Root resorption of second molar as result of impacted
third molar.
Prevention of Odontogenic Cysts and Tumors
When impacted teeth are retained within the alveolar
process, the associated follicular sac is also retained.
Although in most patients the dental follicle maintains
its original size, it may undergo cystic degeneration and
become a dentigerous cyst or keratocyst. If the patient is
closely followed, the dentist can diagnose the cyst
before it reaches large proportions (Fig. 9-11). However,
unmon-itored cysts can reach enormous sizes (Fig. 9-12).
As a general guideline, if the follicular space around the
crown of the tooth is greater than 3 mm, the diagnosis
of a dentigerous cyst is a reasonable one.
In the same way that odontogenic cysts can occur
around impacted teeth, odontogenic tumors can arise
from the epithelium contained within the dental
follicle. The most common odontogenic tumor to
occur in this region is the ameloblastoma. Usually,
ameloblastomas in this area must be treated aggressively
by excision of the overlying soft tissue and of at least a
portion of the mandible. Occasionally, other
odontogenic tumors may occur in conjunction with
impacted teeth (Fig. 9-13).
Although the overall incidence of odontogenic cysts
and tumors around impacted teeth is not high,10 the overwhelming majority of pathologic conditions of the
mandibular third molar are associated with unerupted
teeth. It is therefore recommended that impacted teeth
be removed to prevent the occurrence of cysts and
tumors.
Treatment of Pain of Unexplained Origin
Occasionally, patients come to the dentist complaining
of pain in the retromolar region of the mandible for no
obvious reasons. If conditions such as myofascial pain
dysfunction syndrome and temporomandibular joint
(TMJ) disorder are excluded and if the patient has an
unerupted tooth, removal of the tooth sometimes
results in resolution of the pain.
FIG. 9-7 Root resorption of maxillary lateral incisors as result of
impacted canine.
Prevention of Fracture of the Jaw
An impacted third molar in the mandible occupies space
that is usually filled with bone. This may weaken the
mandible and render the jaw more susceptible to fracture
(Fig. 9-14). If the jaw fractures through the area of an
impacted third molar, the impacted third molar is frequently removed before the fracture is reduced and intermaxillary fixation is applied.
Facilitation of Orthodontic Treatment
In patients who require retraction of first and second
molars by orthodontic techniques, the presence of
impacted third molars may interfere with the treatment.
It is therefore recommended that impacted third molars
be removed before orthodontic therapy is begun.
Another consideration is that, after orthodontic treatment has been concluded, there may be crowding of the
mandibular incisor teeth. This has been attributed to the
mesial force transmitted to the molar and premolar teeth
by impacted third molars, especially mesially inclined
impactions.11-12 Several other factors influence crowding.
Growth of the maxilla stops before growth of the
mandible. If the upper and lower incisors are in a proper
overbite and overjet relationship, and if the mandible
continues to grow after the maxilla stops growing, the
mandibular incisors then become crowded to accommodate the constriction imposed on them by the maxillary
incisors. This explanation appears sound, because crowd-
FIG. 9-8 Impacted tooth retained under denture. Tooth is now at surface and is causing infection.
FIG. 9-9 Impacted tooth under fixed bridge. Tooth must be
removed and therefore may jeopardize bridge.
ing occurs after the age at which the maxilla stops growing
and the mandible continues forward growth.
Many orthodontists still refer their patients to surgeons
for removal of impacted third molars after orthodontic
treatment is complete. Although the surgeon should explain
the other reasons for surgery, the decision to remove
impacted teeth to help prevent crowding should be
supported.
Optimal Periodontal Healing
As noted earlier, one of the most important indications
for removal of impacted third molars is to preserve the
periodontal health. A great deal of attention has been
given to the two primary parameters of
periodontal
FIG. 9-10 Impaction in atrophic mandible, which may result in jaw
fracture during extraction.
health after third molar surgery; that is, bone height on the
distal aspect of the second molar and attachment level
on the distal aspect of the second molar.
Recent studies have provided information on which to
base the likelihood of optimum periodontal tissue healing.13"15 The two most important factors have been shown
to be the extent of the preoperative infrabony defect on
the distal aspect of the second molar and the patient's age
at the time of surgery. If a large amount of distal bone is
missing because of the presence of the impacted tooth and
the associated follicle, it is less likely that the infrabony
pocket can be decreased. Likewise, if the patient is older,
then the likelihood of optimum bony healing is decreased.
Patients whose third molars are removed before age 25 are
more likely to have better bone
FIG. 9-11 Small dentigerous cyst arising around impacted tooth.
FIG. 9-12 Large dentigerous cyst that extends from coronoid
process to mental foramen. Cyst has displaced impacted third molar
to inferior border of mandible.
FIG. 9-13 Large ameloblastoma in mandible as result of impacted
third molar.
healing than those whose impacted teeth are removed
after age 25.14 In the younger patient, not only is the initial periodontal healing better but the long-term continued regeneration of the periodontium is clearly better.14
As mentioned previously, unerupted teeth may continue
to erupt until age 25. Because the terminal portion of
the eruption process occurs relatively slowly, the
chances of developing pericoronitis increase, as do the
amount of contact between the third molar and second
molar. Both of these factors decrease the possibility for
optimum periodontal healing. However, it should be
noted that the completely bony impacted third molar
in a patient older than age 30 should probably be left
in place unless some specific pathology develops.
Removal of such asymptomatic completely impacted
third molars
in older patients will clearly result in pocket depths and
alveolar bone loss, which will be greater than if the tooth
were left in place.
CONTRAINDICATIONS FOR REMOVAL
OF IMPACTED TEETH
All impacted teeth should be removed unless specific
contraindications justify leaving them in position. When
the potential benefits outweigh the potential complications and risks, the procedure should be performed. Similarly, when the risks are greater than the potential benefits, the procedure should be deferred.
Contraindications for the removal of impacted teeth
primarily involve the patient's physical status.
If the impacted tooth shows signs of cystic formation or
periodontal disease involving either the adjacent tooth
or the impacted tooth, if it is a single impacted tooth
underneath a prosthesis with thin overlying bone, or if it
becomes symptomatic as the result of infection, the tooth
must be removed.
Compromised Medical Status
Similar to extremes of age, compromised medical status
may contraindicate the removal of an impacted tooth.
Frequently, compromised medical status and advancing
age go hand-in-hand. If the impacted tooth is asymptomatic, its surgical removal must be viewed as elective. If the
patient's cardiovascular or respiratory function or host
defenses for combating infection are compromised or the
patient has a serious acquired or congenital coagu-lopathy,
the surgeon must consider leaving the tooth in the alveolar
process. On the other hand, if the tooth becomes
symptomatic, the surgeon must work carefully with the
patient's physician to remove the tooth with the least
operative and postoperative medical sequelae.
FIG. 9-14 Fracture of mandible that occurred through location
of impacted third molar.
Extremes of Age
The third molar tooth bud can be radiographically
visualized by age 6. Some surgeons think that removal
of the tooth bud at age 7 to 9 can be accomplished
with minimal surgical morbidity and therefore
should be performed at this age. However, most
surgeons believe that it is not possible to predict
accurately if the forming third molar will be impacted.
The consensus is that very early removal of third molars
should be deferred until an accurate diagnosis of
impaction can be made.
The most common contraindication for the
removal of impacted teeth is advanced age. As a patient
ages the bone becomes highly calcified, therefore less
flexible and less likely to bend under the forces of
tooth extraction. The result is that more bone must be
surgically removed to displace the tooth from its
socket.
Similarly, as patients age, they respond less
favorably and with more postoperative sequelae. An 18year-old patient may have 1 or 2 days of discomfort and
swelling after the removal of an impacted tooth,
whereas a similar procedure may result in a 4- or 5-day
recovery period for a 50-year-old patient.
Finally, if a tooth has been retained in the alveolar
process for many years without periodontal disease,
caries, or cystic degeneration, it is unlikely that these
unfavorable sequelae will occur. Therefore in an older
patient (usually over age 35) with an impacted tooth
that shows no signs of disease and that has a
radiographically detectable layer of overlying bone,
the tooth should not be removed (Fig. 9-15). The dentist
caring for the patient should check the impacted tooth
radiographically every 1 or 2 years to ensure that no
adverse sequela occurs.
Probable Excessive Damage to Adjacent Structures
If the impacted tooth lies in an area in which its removal
may seriously jeopardize adjacent nerves, teeth, or previously constructed bridges, it may be prudent to leave the
tooth in place. When the dentist makes the decision not to
remove a tooth, the reasons must be weighed against
potential future complications. For younger patients who
may suffer the sequelae of impacted teeth, it may be wise to
remove the tooth while taking special measures to prevent
damage to adjacent structures. However, for the older patient
with no signs of impending complications and for whom
the probability of such complications is low, the impacted
tooth should not be removed. A classic example of such a
case is the older patient with a potentially severe periodontal
defect on the distal aspect of the second molar but in
whom removal of the third molar would almost surely
result in the loss of the second molar. In this situation the
impacted tooth should not be removed.
Summary
The preceding discussion of indications and contraindications for the removal of impacted third molars has
been designed to point out that there are various risks and
benefits for removing impacted teeth in patients. Patients
who have one or more pathologic symptoms or problems
should have their impacted teeth removed. Most of the
symptomatic, pathologic problems that result from impacted
third molars occur because of partially erupted teeth and
occur less commonly with a complete bony impaction.
It is less clear what should be done with impacted
teeth before they cause symptoms or problems. In making
a decision as to whether or not an impacted third molar
should be removed, a variety of factors must be considered.
First, the available room in the arch into which the tooth
can erupt must be considered. If adequate room exists,
then the clinician may choose to defer removal of the tooth
until eruption is complete. A second consideration is the
status of the impacted tooth and the
FIG. 9-15 Impacted maxillary right third molar in 63-year-old patient. This molar should not be extracted because it is
deeply embedded and no signs of disease are present.
age of the patient. It is critical to remember that the average age of complete eruption is 20, but that eruption may
continue to occur up to age 25. A tooth that appears to be
a mesioangular impaction at age 17 may eventually become more vertical and erupt into the mouth. If insufficient room exists to accommodate the tooth and a soft
tissue operculum exists over the posterior aspect, then
pathologic sequelae are likely to occur.
Although there have been some attempts at making
very early predictions of whether or not a tooth was
going to be impacted, these efforts have not yet resulted
in a reliable predictive model. However, by the time the
patient reaches age 18, the dentist and surgeon can reasonably predict whether there will be adequate room into
which the tooth can erupt with sufficient clearance of the
anterior ramus to prevent soft tissue operculum formation. At this time, if surgical removal is chosen, soft tissue
and bone tissue healing will occur at its maximal level. At
age 18 or 19, if the diagnosis for inadequate room for
functional eruption can be made, then the asymptomatic
third molar can be removed and the long-term periodontal health of the second molar will be maximized.
CLASSIFICATION SYSTEMS
OF IMPACTED TEETH
Removal of impacted teeth can be either extremely difficult or relatively straightforward and easy. To determine
the degree of difficulty preoperatively, the surgeon
should examine the patient methodically. The primary
factor determining the difficulty of the removal is accessibility. Accessibility is determined by the ease of exposing the tooth, of preparing a pathway for its delivery, and
of preparing a purchase point (or taking advantage of a
natural purchase point). With careful classification of the
impacted teeth using a variety of systems, the surgeon
can approach the proposed surgery in an orderly fashion
and predict whether any extraordinary surgical approach-
es will be necessary or if the patient will encounter any
postoperative problems.
The majority of the classifying results from analysis of
the radiograph. For most situations the periapical radiograph provides adequate detail and should be the radiograph most commonly used. The panoramic radiograph
shows a more accurate picture of the total anatomy of the
region and can be used as an adequate substitute.
For each patient the dentist should carefully analyze
the factors discussed in this section. By combining these
factors, the dentist can assess the difficulty of the surgery
and elect to extract the impacted teeth that are within his
skill level. However, for the patient's sake the dentist
should refer the patient to a specialist if a tooth presents
a difficult surgical problem.
Angulation
The first classification system employs a description of
the angulation of the long axis of the impacted third
molar with respect to the long axis of the second molar.
Because teeth at certain inclinations have ready-made
pathways for withdrawal, whereas pathways for teeth of
other inclinations require the removal of substantial
amounts of bone, this classification system provides an
initial evaluation of the difficulty of extractions.
The mesioangular impaction is generally acknowledged as the least difficult impaction to remove (Fig. 916). The mesioangular-impacted tooth is tilted toward the
second molar in a mesial direction. This type of
impaction is also the most commonly seen and comprises approximately 43% of all impacted teeth.
In a severe mesial inclination the impacted tooth is
horizontal (Fig. 9-17). This type of impaction is usually
considered more difficult to remove than the mesioangular impaction. Horizontal impactions occur less frequently and are only seen in approximately 3% of all mandibular impactions.
FIG. 9-16 A, Mesioangular impaction—most common and easiest impaction to remove. B, Mesioangular impaction is usually in close proximity to second molar.
FIG. 9-17 A, Horizontal impaction—uncommon and more difficult to remove than mesioangular
impaction. B, Occlusal surface of horizontal impacted third molar is usually immediately adjacent to
root of second molar, which often produces early severe periodontal disease.
In the vertical impaction the long axis of the
impacted tooth runs in the same direction as the long
axis of the second molar. This impaction occurs with
the second greatest frequency, accounts for
approximately 38% of all impactions, and is third in
difficulty of removal (Fig. 9-18).
Finally, the distoangular impaction is the tooth with
the most difficult angulation for removal (Fig. 9-19). In
the distoangular impaction the long axis of the third
molar is distally or posteriorly angled away from the
sec-
ond molar. This impaction is the most difficult
remove because the tooth has a withdrawal pathway that
runs into the mandibular ramus, and its removal
requires greater surgical intervention. Distoangular
impactions occur uncommonly and account for
approximately 6% of all impacted third molars. Erupted
third molars may be in a distoangular position. this
occurs, they are extremely difficult to remove tinely,
compared with the removal of other teeth.
B
FIG. 9-18 A, Vertical impaction—second most common impaction and second most difficult to
remove. B, Vertical impaction is frequently covered on its posterior aspect with bone of anterior ramus
of mandible.
FIG. 9-19 A, Distoangular impaction—uncommon and most difficult of the four types to remove.
B, Occlusal surface of distoangular impaction is usually embedded in ramus of mandible and requires
significant bone removal for extraction.
In addition to the relationship between the angulation
of the long axes of the second and third molars, the teeth
can also be angled in a buccal or lingual direction. As is
noted earlier, the linguocortical plate of the mandible
becomes thinner as it progresses posteriorly. Therefore
most mandibular third molars are angled toward the lingual direction or in lingual version. Occasionally, a tooth
is angled toward the buccal aspect of the mandible or in
buccal version.
Rarely a tooth is a transverse impaction, that is, in an
absolutely horizontal position in a buccolingual direction. The occlusal surface of the tooth can face either the
buccal or lingual direction. To determine buccal or lingual version accurately, the dentist must take a perpen-
dicular occlusal film. However, this determination is usually not necessary, because the surgeon can make this
identification early in the operation, and the buccal or
lingual position of the tooth does not greatly influence
the difficulty of the surgery.
Relationship to Anterior Border of Ramus
Another method for classifying impacted mandibular
third molars is based on the amount of impacted tooth
that is covered with the bone of the mandibular ramus.
This classification is known as the Pell and Gregory classification and is sometimes referred to as the Pelt and Gregory classes 1, 2, and 3. For this classification it is important
that the surgeon carefully examine the relationship
between the tooth and the anterior part of the ramus. If
the mesiodistal diameter of the crown is completely anterior to the anterior border of the mandibular ramus, it is
in a class 1 relationship. If the tooth is angled in a vertical direction, the chances for the tooth to erupt into a
normal position are good (Fig. 9-20).
If the tooth is positioned posteriorly so that approximately one half is covered by the ramus, the tooth's relationship with the ramus is class 2. In the class 2 situation
the tooth cannot become completely free from bone,
because a small shelf of bone overlies the distal portion of
the tooth (Fig. 9-21). A class 3 relationship between the
tooth and ramus occurs when the tooth is located completely within the mandibular ramus (Fig. 9-22). It should
be obvious that the class 1 relationship will provide the
greatest accessibility to the impacted tooth and therefore
will be easiest to remove. The class 3 relationship provides the least accessibility and therefore presents the
greatest difficulty.
FIG. 9-20 Pell and Gregory class 1 impaction. Mandibular third
molar has sufficient anteroposterior room (i.e., anterior-to-anterior
border of ramus) to erupt.
Pell and Gregory class 2 impaction.
Approximately half is covered by anterior portion of
ramus of mandible.
FIG. 9-21
Relationship to Occlusal Plane
The depth of the impacted tooth compared with the
height of the adjacent second molar provides the next
classification system for determining the difficulty of
impaction removal. This classification system was also
suggested by Pell and Gregory and is called Pell and Gregory A, B, and C classification. In this classification the
degree of difficulty is measured by the thickness of the
overlying bone; that is, the degree of difficulty increases as the depth of the impacted tooth increases. As the
tooth becomes less accessible and it becomes more difficult to section the tooth and to prepare purchase
points, the overall difficulty of the operation increases
substantially.
A class A impaction is one in which the occlusal surface of the impacted tooth is level or nearly level with the
occlusal plane of the second molar (Fig. 9-23). A class B
impaction is an impacted tooth with an occlusal surface
between the occlusal plane and the cervical line of the
second molar (Fig. 9-24). Finally, the class C impaction is
FIG. 9-22 Pell and Gregory class 3 impaction. Impacted third
molar is completely embedded in bone of ramus of mandible.
Pell and Gregory class A impaction.
Occlusal plane of impacted tooth is at same level as
occlusal plane of second molar.
FIG. 9-23
one in which the occlusal surface of the impacted tooth
is below the cervical line of the second molar (Fig. 9-25).
Summary
The three classification systems discussed so far are used
in conjunction to determine the difficulty of an extraction. For example, a mesioangular impaction with a class
1 ramus and a class A depth is easy to remove and is
essentially the extraction of an erupted tooth (Fig. 9-26).
However, as the ramus relationship changes to a class 2
and the depth of the impaction increases to a class B, the
degree of difficulty becomes greater. A horizontal
impaction with a class 2 ramus relationship and a class B
depth is a moderately difficult extraction and one that
most general practitioners do not want to attempt (Fig.
9-27). Finally, the most difficult of all impactions is a distoangular impaction with a class 3 ramus relationship at
a class C depth. Even specialists view removing this tooth
as a surgical challenge (Fig. 9-28).
FIG. 9-24 Pell and Gregory class B impaction. Occlusal plane of
impacted tooth is between occlusal plane and cervical line of second
molar.
FIG. 9-25 Pell and Gregory class C impaction. Impacted tooth is
below cervical line of second molar.
FIG. 9-26 Mesioangular impaction with class 1 ramus relationship
and class A depth. All three classifications make it easiest type of
impaction to remove.
FIG. 9-27 Horizontal impaction with class 2 ramus relationship
and class B depth makes it moderately difficult to extract.
FIG. 9-28 Impaction with distoangular, class 3 ramus relationship
and class C depth makes it extremely difficult to remove.
ROOT MORPHOLOGY
Just as the root morphology of the erupted tooth has a
major influence on the degree of difficulty of a closed
extraction, root morphology plays a major role in determining the degree of difficulty of the impacted tooth's
removal. Several factors must be considered when assessing the morphologic structure of the root.
The first consideration is the length of the root. As discussed earlier, the optimal time for removal of an impacted tooth is when the root is one third to two thirds
formed. When this is the case, the ends of the roots are
blunt and almost never fracture (Fig. 9-29). If the tooth is
not removed during the formative stage and the entire
length of the root develops, the possibility increases for
abnormal root morphology and for fracture of the root
tips during extraction. If the root development is insufficient (i.e., less than one third complete), the tooth is more
difficult to remove, because it tends to roll in its crypt like
a ball in a socket, which prevents easy elevation (Fig. 930). The next factor to be assessed is whether the roots are
fused into a single, conic root (Fig. 9-31), or if they are
separate and distinct roots. The fused, conic roots are easier to remove than widely separate roots (Fig. 9-32).
The curvature of the tooth roots also plays a role in the
difficulty of the extraction. Severely curved or dilacerated
roots are more difficult to remove than straight or slightly curved roots (see Fig. 9-32). The surgeon should carefully examine the apex area of the radiograph to assess
FIG. 9-29 Roots that are two thirds formed, which are less difficult
to remove.
FIG. 9-30 Lack of root development. If extraction is attempted,
crown will roll around in crypt, which makes it difficult to remove.
FIG. 9-31 Fused roots with conic shape.
the presence of small, abnormal, and sharply hooked
roots that probably fracture if the surgeon does not give
them special consideration.
The direction of the tooth root curvature is also important to examine preoperatively. During removal of a
mesioangular impaction, roots that are curved gently in the
distal direction (following along the pathway of extraction)
can be removed without the force that can cause fracture of
the roots. However, if the roots of a mesioangular
impaction are curved mesially, the roots almost always fracture or must be sectioned before the tooth can be delivered.
The total width of the roots in the mesiodistal direction
should be compared with the width of the tooth at the
cervical line. If the tooth root width is greater, the extrac-
tion will be more difficult. More bone must be removed or
the tooth must be sectioned before extraction.
Finally, the surgeon should assess the periodontal ligament space. Although in most patients the periodontal
ligament space is of normal dimensions, it sometimes is
wider or narrower. The wider the periodontal ligament
space, the easier the tooth is to remove (Fig. 9-33). A third
molar that is in the proper stage of development for
removal has a relatively broad periodontal ligament
space, which eases extraction. However, older patients,
especially those over age 40, tend to have a much narrower periodontal ligament space, which thereby increases the difficulty of the extraction.
Size of Follicular Sac
The size of the follicle around the impacted tooth can
help determine the difficulty of the extraction. If the follicular sac is wide (almost cystic in size), much less bone
must be removed, which makes the tooth easier to extract
(Fig. 9-34). (Young patients are more likely to have large
follicles, which is another factor that makes extractions
easier in younger patients.) However, if the follicular
space around the crown of the tooth is narrow or nonexistent, the surgeon must create space around the entire
crown, which increases both the difficulty of the procedure and the time required to remove the tooth. The surgeon must carefully examine the follicle size when determining the difficulty of an extraction.
Density of Surrounding Bone
FIG. 9-32 Divergent roots with severe curvature. Such roots are
more difficult to remove.
The density of the bone surrounding the tooth plays a
role in determining the difficulty of the extraction.
Although some clues can be seen on the radiographs,
variations in radiograph density and angulation render
interpretations based on radiographs unreliable. Bone
density is best determined by the patient's age. Patients
FIG. 9-33 Wide periodontal ligament space. Such space makes extraction
process less difficult.
who are 18 years of age or younger have bone densities
favorable for tooth removal. The bone is less dense, is
more likely to be pliable, and expands and bends somewhat, which allows the socket to be expanded by elevators or by luxation forces applied to the tooth itself. Additionally, the bone is easier to cut with a dental drill and
can be removed more rapidly than denser bone.
Conversely, patients who are older than age 35 have
denser bone and thus decreased flexibility and ability to
expand. In these patients the surgeon must remove all
interfering bone, because it is not possible to expand the
bony socket. In addition, as the bone increases in density, it becomes more difficult to remove with a dental drill,
and the bone removal process takes longer.
Contact with Mandibular Second Molar
If space exists between the second molar and the impacted
third molar, the extraction will be easier. However, if the
tooth is a mesioangular or horizontal impaction, it is frequently in direct contact with the adjacent second molar. To
remove the third molar safely without injuring the second
molar, the surgeon must be cautious with pressure from elevators or with the bur when removing bone. If the second
molar has caries or a large restoration or root canal, the surgeon must take special care not to fracture the restoration
or a portion of the carious crown (see Fig. 9-17, B).
Relationship to Inferior Alveolar Nerve
Impacted mandibular third molars frequently have roots
that are superimposed on the inferior alveolar canal on
radiographs. Although the canal is usually on the buccal
aspect of the tooth, it is in close proximity to the tooth,
Therefore one of the potential sequelae of impacted third
molar removal is damage to or bruising of the inferior
alveolar nerve. This usually results in some altered sensation (paresthesia or anesthesia) of the lower lip on the
injured side. Although this altered sensation is usually
brief (lasting only a few days), it may extend for weeks or
months; on rare occasions it can be permanent. If the
root ends of the tooth appear to be close to the inferior
alveolar nerve, the surgeon must take special care to
avoid injuring the nerve (Fig. 9-35), which makes the
procedure more difficult.
Nature of Overlying Tissue
FIG. 9-34 Large follicular sac. When space of sac is large, amount
of required bone removal is decreased.
The preceding systems all classify factors that make third
molar extraction easier or more difficult. The classification system discussed in this section does not fit into this
category. However, it is the system used by most dental
insurance companies and the one by which the surgeon
charges for his services.
FIG. 9-35 A, Radiographic view of mandibular third molar suggests that it is surrounding or adjacent to inferior alveolar
neurovascular canal. B, Hole and indentation in two roots of mandibular third molar indicate position of roots of this tooth
to inferior alveolar canal. When this tooth was removed, inferior alveolar neurovascular bundle was severed (not same
tooth as shown in A).
According to this scheme, the, three types of impactions are (1) soft tissue impaction, (2) partial bony
impaction, and (3) full bony impaction. An impaction is
defined as a soft tissue impaction when the height of the
tooth's contour is above the level of the alveolar bone,
and the superficial portion of the tooth is covered only by
soft tissue (Fig. 9-36). To remove the soft tissue
impaction, the surgeon must incise the soft tissue and
reflect a small soft tissue flap to obtain access to the tooth
to elevate it from its socket. The soft tissue impaction is
usually the easiest of the three extractions.
The partial bone impaction occurs when the superficial portion of the tooth is covered by soft tissue, but the
height of the tooth's contour is below the level of the surrounding alveolar bone (Fig. 9-37). To remove the tooth,
the surgeon must incise the soft tissue, reflect a soft tissue
flap, and remove the bone above the height of the contour. The surgeon may need to divide the tooth in addition to removing bone.
The complete bone impaction is an impacted tooth
that is completely encased in bone so that, when the
surgeon reflects the soft tissue flap, no tooth is visible
(Fig. 9-38). To remove the tooth, extensive amounts of
bone must be removed and the tooth almost always
must be sectioned. The complete bony impaction is
often the most difficult to remove.
Although this classification is extensively used, it frequently has no relationship to the difficulty of the
extraction (Boxes 9-1 and 9-2). The parameters of
angulation,
FIG. 9-36 Soft tissue impaction in which crown of tooth is
covered by soft tissue only and can be removed without bone
removal.
Factors that Make Impaction Surgery Less Difficult
FIG. 9-37 Partial bony impaction in which part of tooth, usually
posterior aspect, is covered with bone and requires either bone
removal or tooth sectioning for extraction.
'Present In the young patient.
Factors that Make Impaction Surgery More Difficult
*Present in older patients.
FIG. 9-38 Complete bony impaction in which tooth is
completely covered with bone and requires extensive removal
of bone for extraction.
FIG. 9-39 A, Vertical impaction of maxillary third molar. This angle accounts for 63% of impactions.
B, Distoangular impaction of maxillary third molar. This angle accounts for 25% of impactions.
C, Mesioangular impaction of maxillary third molar. This angle accounts for 12% of impactions.
ramus relationship, root morphology, and patient age
are more important than this system. The surgeon
should use all of the information available to determine
the difficulty of the proposed surgery.
MODIFICATION
OF
CLASSIFICATION
SYSTEMS
FOR MAXILLARY IMPACTED TEETH
The classification systems for the maxillary impacted
third molar are essentially the same as for the impacted
mandibular third molar. However, several distinctions
and additions must be made to assess more accurately
the difficulty of removal during the treatmentplanning phase of the procedure.
Concerning angulation, the three types of maxillary
third molars are (1) the vertical impaction (Fig. 9-39, A),
(2) the distoangular impaction (Fig. 9-39, B), and (3) the
mesioangular impaction (Fig. 9-39, C). The vertical
impaction occurs approximately 63% of the time, the
dis-toangular
approximately
25%,
and
the
mesioangular position approximately 12% of the time.
Rarely other posi-tions, such as a transverse, inverted, or
horizontal position, are encountered; these unusual
positions account for less than 1% of impacted
maxillary third molars.
The same angulations in mandibular third molar
extractions cause opposite degrees of difficulty for
maxillary third molar extractions. Vertical and
distoangular impactions are the easiest to remove,
whereas mesioan-gular impactions are the most
difficult (exactly the oppo-site of impacted mandibular
third molars). Mesioangular impactions are more
difficult to remove because the bone that overlies the
impaction and that must be removed or expanded is on
the posterior aspect of the tooth and is much heavier
than in the vertical or distoangular im-paction. In
addition, access to the mesioangularly positioned tooth
is more difficult.
The position of the maxillary third molar in a buccopalatal direction is also important for determining the
difficulty of the removal. Most maxillary third molars
are angled toward the buccal aspect of the alveolar
process, which makes the overlying bone in that area
thin and therefore easy to remove or to expand.
Occasionally, the impacted maxillary third molar is
positioned toward the
palatal aspect of the alveolar process. This makes the tooth
much more difficult to extract, because greater amounts of
bone must be removed to gain access to the underlying
tooth. A combination of radiographic assessment and clinical digital palpation of the tuberosity area can determine
if the maxillary third molar is in the buccopalatal position.
If the tooth is positioned toward the buccal, a definite palpable bulge is found in the area; if the tooth is palatally
positioned, a bony deficit is found in that region. When
either is determined by clinical examination, the surgeon
must anticipate a longer, more difficult procedure.
The Pell and Gregory A, B, and C classification used to
diagnose the depth of impaction in the mandible is also
used in the maxilla (Fig. 9-40). Preoperative assessment of
the remaining classifications is the same. The factors that
influence the difficulty of mandibular impacted third
molar removal are the same for maxillary third molar
removal. For example, the individual impacted tooth root
morphology plays a substantial role in determining the
degree of extraction difficulty. The most common factor
that causes difficulty with maxillary third molar removal
is a thin, nonfused root with erratic curvature (Fig. 9-41).
The majority of maxillary third molars have fused roots
that are conic. However, the surgeon should examine the
preoperative radiograph carefully to ensure that this is
the situation with each individual impaction. The surgeon should also check the periodontal ligament, because
the wider the ligament space the less difficult the tooth is
to remove. In addition, similar to mandibular third
molars, the periodontal ligament space tends to decrease
as the patient increases in age.
The follicle surrounding the crown of the impacted
tooth also has an influence on the difficulty of the
extraction. If the follicular space is broad, the tooth will
be easier to remove than if the follicular space is thin or
nonexistent.
Bone density is also an important factor in maxillary
impaction removal and is related closely to the age of the
patient. The younger the patient, the less dense and more
elastic—and therefore more expandable—is the bone surrounding the impacted third molar. As the patient ages,
the bone becomes denser and less elastic, and the tooth
becomes more difficult to remove.
FIG. 9-40 A, Pell and Gregory class A occlusal surface of third molar is at same level as that of second molar. B, Pell and Gregory class B occlusal surface of third molar is located between occlusal plane
and cervical line of second molar. C, Pell and Gregory class C impacted maxillary third molar is deep
to cervical line of second molar.
The relationship to the adjacent second molar tooth
also influences the difficulty of the extraction. It may
require that additional bone be removed to displace
the tooth from underneath the second molar. In
addition, because the use of elevators is common in the
removal of maxillary third molars, the surgeon must be
aware of the existence of large restorations or caries in
the adjacent second molar. Injudicious use of elevators
can result in the fracture of restorations or carious
teeth.
The type of impaction, with respect to overlying tissue, must also be considered for maxillary third molars.
The classification system used for mandibular teeth is
the same as the system that is used for maxillary teeth:
soft tissue impaction, partial bony impaction, and
complete bony impaction. The definitions of these
types of impactions are precisely the same as those
used for the mandibular third molars.
Two additional factors influence the difficulty of
maxillary third molar removal but do not exist for the
mandibular third molars. Both are related to the
structure and position of the maxillary sinus. First, the
maxillary sinus is in intimate contact with the roots of
the molar teeth; and, frequently, the maxillary third
molar actually forms a portion of the posterior sinus
wall. If this is the case, removal of the maxillary third
molar may result in maxillary sinus complications, such
as sinusitis or an oroantral fistula. The presence of the
maxillary sinus does not necessarily make the removal
of the impacted tooth more difficult, but it increases the
likelihood of postoperative complications and
morbidity.
Finally, in maxillary third molar removal, the
tuberos-ity of the posterior maxilla can be fractured.
Such fractures are possible, especially when dense and
nonelastic bone exists, such as in older patients. In
addition, a large maxillary sinus makes the
surrounding alveolar bone thin and more susceptible
to fracture when excessive force is applied. A root
morphology that is not fused but has divergent roots
requires greater force to remove and can make fracture
more likely. In addition, mesioangular impactions
increase the possibility of fractures (see Fig. 9-39, C). In
these situations the overlying tuberosity is heavier,
but the surrounding bone is usually thinner. When
the surgeon prepares a purchase point at the
FIG. 9-41 The maxillary third molar has the most erratic and
bizarre root formation of all teeth.
mesiocervical line, fracture of the tuberosity becomes a
greater risk if: (1) the bone is nonelastic (as in older
patients), (2) the tooth is multirooted with large
bulbous roots (as in older patients), (3) the maxillary
sinus is large and expanded to include the roots of the
impacted third molar, or (4) the surgeon has to use
excessive force to ele-vate the tooth. Management of
the fractured tuberosity is discussed in Chapter 11.
FIG. 9-42 A, Labially positioned impacted maxillary canine. Tooth should be uncovered
with apical-ly positioned flap procedure to preserve attached gingiva. B, Mucoperiosteal
flap is outlined, allowing for repositioning of keratinized mucosa over exposed tooth. C,
When flap is reflected, thin overlying bone is removed. D, Tissue is retracted and
bonded to tooth with a wire or with a gold chain (E).
F, Flap is apically sutured to tooth.
Continued
FIG. 9-42—cont'd C, After 6 months, exposed tooth is in desired
position, with broad zone of attached gingiva.
DIFFICULTY OF REMOVAL OF OTHER
IMPACTED TEETH
After the mandibular and maxillary third molars, the next
most commonly impacted tooth is the maxillary canine.
If the patient seeks orthodontic care, the orthodontist
will frequently request that the maxillary canine simply
have the overlying soft and hard tissue removed so
that the tooth can be manipulated into its proper
position by orthodontic appliances. When the tooth is
positioned in such a way that orthodontic manipulation
can assist the proper positioning of the impacted canine,
the tooth is exposed and bracketed (Fig. 9-42, A). A fourcorner flap is created to allow the soft tissue to be
repositioned apically should this be required for
maximum keratinized tissue management (Fig. 9-42, B).
The overlying bone tissue is then removed with chisel or
burs as is necessary (Fig. 9-42, C). Once the area is
debrided, the surface of the tooth is prepared by the
usual standard procedures of etching and applying
primer. The bracket is then luted to the surface of the tooth
(Fig. 9-42, D). A wire can be used to connect the bracket
to the orthodontic appliance or more commonly a gold
chain is attached from the orthodontic bracket to the
orthodontic arch wire. The gold chain provides a greater
degree of flexibility and the incidence of breakage of the
chain is much less than breakage of a wire. The soft tissue
is then sutured in such a way as to provide the maximum
coverage of the exposed tissue with keratinized tissue (Fig.
942, E). As the tooth is pulled into place with the orthodontic appliances, the soft tissue surrounding the newly
positioned tooth should have adequate keratinized tissue
and the tooth should be in an ideal position.
If the tooth is positioned toward the palatal aspect, the
tooth may be either repositioned or removed. If the tooth
is repositioned, it is surgically exposed and moved into
position orthodontically. In this procedure the overlying
soft tissue is excised; flaps are not needed to gain attached
tissue. Because the bone in the palate is thicker, a bur is
usually necessary to remove the overlying bone. The
exposed tooth then is managed in the same manner as is
the labially positioned tooth.
If the dentist decides the tooth should be removed, it
must be determined if the tooth is positioned labially,
toward the palate, or in the middle of the alveolar
process. If the tooth is on the labial aspect, it is easy to
reflect a soft tissue flap and to remove the underlying
bone and the tooth. However, if the tooth is on the
palatal aspect or in the intermediate buccolingual
position, it is much more difficult to remove. Therefore
when assessing the impacted maxillary canine for
removal, the surgeon's most important assessment is of
the buccolin-gual position of the tooth.
Similar considerations are necessary for other impactions, such as mandibular premolars and
supernumerary teeth. The supernumerary tooth in the
midline of the maxilla, called a mesiodens, is almost
always found on the palate and should be approached
from a palatal direction when it is removed.
SURGICAL PROCEDURE
The principles and steps for removing impacted teeth
are the same as for other surgical extractions. Five basic
steps make up the technique: The first step is to have
adequate exposure of the area of the impacted tooth.
This means that the reflected soft tissue flap must be of
an adequate dimension to allow the surgeon to retract
the soft tissue and perform the necessary surgery. The
second step is to assess the need for bone removal and
to remove a sufficient amount of bone to expose the
tooth for sectioning and delivery. The third step is to
divide the tooth with a bur or chisel to allow the tooth
to be extracted without removing excessive amounts of
bone. In the fourth step the sectioned tooth is delivered
from the alveolar process with the appropriate elevators.
Finally, in the fifth step the wound is thoroughly
cleansed with irrigation and mechanical debridement
with a curette and is closed with simple interrupted
sutures. The following discussion elaborates on these
steps for the removal of impacted third molars.
Although the surgical approach to the removal of
impacted teeth is similar to other surgical tooth
extractions, it is important to keep in mind several
distinct differences. For instance, the typical surgical
extraction of a tooth or tooth root requires the removal
of a relatively small amount of bone. However,
when an impacted tooth (especially a mandibular
third molar) is extracted, the amount of bone that must
be removed to deliver the tooth is substantially
greater. This bone is also much denser than it is for
typical surgical extractions, and its removal requires
better instrumentation and a higher degree of surgical
skill.
Impacted teeth also frequently require sectioning,
whereas other types of tooth extractions do not.
Although erupted maxillary and mandibular molars
are occasionally divided for removal, it is not a
routine step in the extraction of these teeth. However,
with impacted mandibular third molars, the surgeon
is required to divide the tooth in a substantial majority
of patients. The surgeon must therefore have the
necessary equipment for such sectioning and the
necessary skills and experience for dividing the tooth
along the proper planes.
Unlike most other types of surgical tooth
extractions, for an impacted tooth removal the surgeon
must be able to balance the degree of bone removal and
sectioning. Essen-
tially, all impacted teeth can be removed without
sectioning if a large amount of bone is removed.
However, the removal of excessive amounts of bone
unnecessarily prolongs the healing period and may result
in a weakened jaw. Therefore the surgeon should
remove most mandibular third molars only after
sectioning them. On the other hand, removal of a
small amount of bone with multiple divisions of the
tooth may cause the tooth sectioning process to take an
excessively long time, thus unnecessarily prolonging the
operation. The surgeon must remove an adequate
amount of bone and section the tooth into a reasonable
number of pieces, both to hasten healing and to
minimize the time of the surgical procedure.
Step 1: Reflecting adequate flaps for accessibility. The dif-
ficulty of removing an impacted tooth depends on its
accessibility. To gain access to the area and to
visualize the overlying bone that must be removed, the
surgeon must reflect an adequate mucoperiosteal flap.
The reflection must be of a dimension adequate to
allow the placement and stabilization of retractors and
instruments for the removal of bone.
In most situations the envelope flap is the preferred
technique. The envelope flap is easier to close and heals
better than the three-cornered flap. However, if the surgeon requires greater access to the more apical areas of
the tooth, which might stretch and tear the envelope
flap, the surgeon should consider using a three-cornered
flap.
The preferred incision for the removal of an impacted
mandibular third molar is an envelope incision that
extends from the mesial papilla of the mandibular first
molar, around the necks of the teeth to the distobuccal
line angle of the second molar, and then posteriorly to
and laterally up the anterior border of the mandible (Pig.
9-43, A).
The incision must not continue posteriorly in a
straight line, because the mandible diverges laterally.
An incision that extends straight posteriorly falls off
the bone and into the sublingual space and may
damage the lingual nerve, which is in close proximity
to the mandible in the area of the third molar. If this
nerve is traumatized, the patient will probably have a
lingual nerve anesthesia, which may be distracting to
the patient. The incision must always be on bone;
therefore the surgeon should carefully palpate the
retromolar area before beginning the incision.
The flap is laterally reflected to approximately the
external oblique ridge with a periosteal elevator (Fig. 943, B). The surgeon should not reflect beyond the
external oblique ridge, because this results in increased
morbidity and an increased number of complications
after surgery. The retractor is placed on the buccal shelf,
just at the external oblique ridge, and it is stabilized by
applying pressure toward the bone, which results in a
retractor that is stable and does not continually
traumatize the soft tissue.
The Austin and the Minnesota retractors are the
most commonly used for flap reflection when
removing mandibuiar third molars.
If the impacted third molar is deeply embedded in
bone and requires more extensive bone removal, a
releasing incision may be useful (Fig. 9-43, C and D).
The flap created by this incision can be reflected farther
apically, without risk of tearing the tissue. The
recommended incision for the maxillary third molar is
also an envelope incision. It extends posteriorly from
the distobuccal line angle of the second molar and
anteriorly to the mesial aspect of the first molar {Fig.
9-44, A and B). In situations in which greater access is
required (e.g., in a deeply embedded impaction), a
release incision extending from the mesial aspect of the
second molar can be used (Fig. 9-44, C and D).
In the removal of third molars it is vital that the flap
be large enough for adequate access and visibility of the
surgical site. The flap must have a broad base if a
releasing incision is used. The incision must be made
with a smooth stroke of the scalpel, which is kept in
contact with bone throughout the entire incision so that
the mucosa and periosteum are completely incised. This
allows a full-thickness mucoperiosteal flap to be
reflected. The incision should be designed so that it can
be closed over solid bone (rather than over a bony
defect). This is achieved by extending the incision at
least one tooth anterior to the surgical site when a
vertical releasing incision is used. The incision should
avoid vital anatomic structures. Only a single releasing
incision should be used.
Step 2: Removal of overlying bone. Once the soft tissue is
elevated and retracted so that the surgical field can be
visualized, the surgeon must make a judgment concerning the amount of bone to be removed. In some situations the tooth can be sectioned with a chisel and delivered without bone removal. In most cases, however,
some bone removal is required.
Although chisels can be used to remove bone overlying
impacted teeth, most surgeons and patients prefer that
bone be removed with a drill. The preferred instrument is
a handpiece with adequate speed, high torque, and the
ability to be sterilized completely, usually in a steam
autoclave.
The bone on the occlusal aspect and on the buccal
and distal aspects down to the cervical line of the
impacted tooth should be removed initially. The
amount of bone that must be removed varies with the
depth of the impaction, the morphology of the roots,
and the angula-tion of the tooth. Bone should not be
removed from the lingual aspect of the mandible
because of the likelihood of damaging the lingual
nerve.
The burs that are used to remove the bone overlying
the impacted tooth vary with surgeons' preferences. A
large round bur, such as a no. 8, is desirable, because it is
an end-cutting bur and can be effectively used for
drilling with a pushing motion. The tip of a fissure bur,
such as a no. 703 bur, does not cut well, but the edge
rapidly removes bone and quickly sections teeth when
used in a lateral direction,
The typical bone removal for the extraction of an
impacted mandibular tooth is illustrated in Fig. 9-45.
The bone on the occlusal aspect of the tooth is
removed first to expose the crown of the tooth. Then
the cortical bone on the buccal aspect of the tooth is
removed down to the cervical line. Next, the bur can be
used to remove bone between the tooth and the cortical
bone in the cancellous area of the bone with a maneuver
called ditching. This provides access for elevators to
gain purchase points and a pathway for delivery of the
tooth. No bone is removed from the lingual aspect so as
to protect the lingual nerve from injury.
FIG. 9-43 A, Envelope incision is most commonly used to reflect soft tissue for removal of impacted
third molar. Posterior extension of incision should laterally diverge to avoid injury to lingual nerve.
B, Envelope incision is laterally reflected to expose bone overlying impacted tooth. C, When threecornered flap is made, a releasing incision is made at mesial aspect of second molar. D, When soft tissue flap is reflected by means of a releasing incision, greater visibility is possible, especially at apical
aspect of surgical field.
FIG. 9-44 A, Envelope flap is most commonly used flap
for removal of maxillary impacted teeth. B, When soft
tissue is reflected, bone overlying third molar is easily
visualized. C, If tooth is deeply impacted, a releasing
incision can be used to gain greater access. D, When
three-cornered flap is reflected, the bone's more apical
portions become more visible.
FIG. 9-45 A, After soft tissue has been reflected, bone overlying
occlusal surface of tooth is removed with a fissure bur. B, Bone on
buccodistal aspect of impacted tooth is then removed with bur.
For maxillary teeth, bone is removed primarily on the
buccal aspect of the tooth, down to the cervical line to
expose the entire clinical crown. Additional bone must be
removed on the mesial aspect of the tooth to allow an
elevator an adequate purchase point to deliver the tooth.
Because the bone overlying maxillary teeth is usually
thin, it can be easily removed with a unibevel chisel with
only hand pressure.
Step 3: Sectioning the tooth. Once sufficient amounts
of bone have been removed from around the
impacted tooth, the surgeon should assess the need to
section the tooth. Sectioning allows portions of the
tooth to be removed separately with elevators through
the opening provided by bone removal.
The direction in which the impacted tooth should be
divided depends primarily on the angulation of the
impacted tooth. Although minor modifications are necessary for teeth with divergent roots or for teeth that are
more or less deeply impacted, the most important determinant is the tooth's angulation.
Tooth sectioning can be performed with either a bur
or chisel; however, the bur is used by most surgeons. If
a chisel is used, it must be extremely sharp, and the
blows delivered to it by the mallet must be sharp and
FIG. 9-46 A, When removing mesioangular impaction, buccodistal bone is removed to expose crown of tooth to cervical
line. B, Distal aspect of crown is then sectioned from tooth. Occasionally, it is necessary to section entire tooth into two
portions rather than to section distal portion of crown only. C, After distal portion of crown has been delivered, small
straight elevator is inserted into purchase point on mesial aspect of third molar, and tooth is delivered with rotational and
lever motion of the elevator.
forceful enough to split the tooth. For the conscious
patient the sound of the chisel striking the tooth may be
bothersome.
When the bur is used, the tooth is sectioned three
fourths of the way toward the lingual aspect. A straight elevator is inserted into the slot made by the bur and rotated
to split the tooth. The bur should not be used to section
the tooth completely through in the lingual direction,
because this is more likely to injure the lingual nerve.
The mesioangular impaction is usually the least difficult
to remove of the four basic angulation types. After sufficient
bone has been removed, the distal half of the crown is sectioned off at the buccal groove to just below the cervical line
on the distal aspect. This portion is delivered. The remainder
of the tooth is removed with a no. 301 elevator placed at the
mesial aspect of the cervical line. A mesioangular impaction
can also be removed by preparing a purchase point in the
tooth with the drill and using a Crane pick elevator to elevate the tooth from the socket (Fig. 9-46).
The next most difficult impaction to remove is the
horizontal impaction. After sufficient bone has been
removed down to the cervical line to expose the superior aspect of the distal root and the majority of the buccal surface of the crown, the tooth is sectioned by dividing the crown of the tooth from the roots at the cervical
line. The crown of the tooth is removed, and the roots
are displaced with a Cryer elevator into the space previously occupied by the crown. If the roots of an impacted
third molar are divergent, they may require sectioning
into two separate portions to be delivered individually
(Fig. 9-47).
The vertical impaction is one of the two most difficult
impactions to remove. The procedure of bone removal
and sectioning is similar to the mesioangular impaction;
that is, the occlusal buccal and distal bone is removed.
The distal half of the crown is sectioned and removed,
and the tooth is elevated by applying an elevator at the
mesial aspect of the cervical line of the tooth. This is
more difficult than a mesioangular removal, because
access around the mandibular second molar is difficult to
obtain and requires the removal of substantially more
bone on the buccal and distal sides (Fig. 9-48).
FIG. 9-47 A, During removal of horizontal impaction, bone overlying tooth (i.e., bone on distal
and buccal aspect of tooth) is removed with bur. B, Crown is then sectioned from roots of tooth
and delivered from socket. C, Roots are then delivered together or independently by Cryer
elevator used with rotational motion. Roots may require separation into two parts; occasionally,
purchase point is made in root to allow Cryer elevator to engage it. D, Mesial root of tooth is
elevated in similar fashion.
FIG. 9-48 A, When removing vertical impaction, the bone on the occlusal, buccal, and distal aspects
of crown is removed, and the tooth is sectioned into mesial and distal sections. if the tooth has a
single-fused root, the distal portion of crown is sectioned off in a manner similar to that depicted for
mesioangular impaction. B, Posterior aspect of the crown is elevated first with Cryer elevator inserted
into small purchase point in distal portion of the tooth. C, Small straight elevator no. 301 is then used
to elevate the mesial aspect of the tooth by rotary-and-lever type of motion.
The most difficult tooth to remove is the
distoangular impaction. After sufficient bone is
removed from the buc-coocclusal and the distal sides of
the tooth, the crown is sectioned from the roots just
above the cervical line. The entire crown is usually
removed, because it interferes with visibility and
access to the root structure of the tooth. If the roots
are fused, a Cryer or straight elevator can be used to
elevate the tooth into the space previously occupied by
the crown. If the roots are divergent, they are usually
sectioned into two pieces and individually delivered.
Extracting this impaction is difficult, because much
distal bone must be removed and the tooth tends to
be elevated distally and into the ramus portion of the
mandible (Fig. 9-49).
Impacted maxillary teeth are rarely sectioned, because
the overlying bone is usually thin and relatively elastic.
In situations in which the bone is thicker or the patient
is older (and therefore the bone not so elastic), tooth
extraction is usually accomplished by bone removal
rather than tooth sectioning. Under no circumstances
should a chisel be used to section maxillary teeth,
because displacement of the tooth into the maxillary
sinus is highly likely.
In general, impacted teeth elsewhere in the mouth are
usually sectioned only at the cervical line. This permits
removal of the crown portion of the tooth, displacement
of the root portion into the space previously occupied by
the crown, and removal of the root portion.
FIG. 9-49 A, For distoangular impaction, occlusal, buccal, and distal bone is removed with bur. It is
important to remember that more distal bone must be taken off than for vertical or mesioangular
impaction. B, Crown of tooth is sectioned off with bur, and crown is delivered with straight elevator.
C, Purchase point is put into remaining root portion of tooth, and roots are delivered by Cryer elevator
with wheel-and-axle type of motion. If roots diverge, it may be necessary in some cases to split
them into independent portions.
Step 4: Delivery of the sectioned tooth with elevator. Once
adequate bone has been removed to expose the tooth and
the tooth has been sectioned in the appropriate fashion,
the tooth is delivered from the alveolar process with dental elevators. In the mandible the most frequently used
elevators are the straight elevator, the paired Cryer elevator, and the Crane pick.
An important difference between the removal of an
impacted mandibular third molar and of a tooth elsewhere in the mouth is that almost no luxation of the
tooth occurs for the purpose of expansion of the buccal
or linguocortical plate. Instead bone is removed and teeth
are sectioned to prepare an unimpeded pathway for delivery of the tooth.
Application of excessive force may result in unfavorable fracturing of the tooth, of excessive buccal bone, of
the adjacent second molar, or possibly of the entire
mandible.
Elevators are designed not to deliver excessive force but
to engage the tooth or tooth root and to apply force in the
proper direction. Some highly skilled surgeons use the periapical curette to remove sectioned roots from their sockets.
Because the impacted tooth has never sustained occlusal
forces, the periodontal ligament is weak and permits the
easy displacement of the tooth root if appropriate bone is
removed and force is delivered in the proper direction.
Delivery of maxillary third molars is accomplished
with small straight elevators such as the no. 301 elevator,
will pull free from the surrounding hard and soft tissue.
A final irrigation and a thorough inspection should be
performed before the wound is closed.
The surgeon should check for adequate hemostasis.
Bleeding can occur from a vessel in the flap, from the
bone marrow that has been cut with a bur, or the inferior
alveolar nerve. Specific bleeding points should be controlled if they exist. If brisk generalized ooze is seen, after
the sutures are placed the surgeon should apply firm pressure with a small, moistened gauze pack. Postoperative
bleeding occurs relatively frequently after third molar
extraction, and therefore adequate hemostasis at the time
of the operation is important.
Usually the closure of the incision should be a primary
closure. If the flap was well designed and not traumatized
during the surgical procedure, it will fit into its original
position. The initial suture should be placed through the
attached tissue on the posterior aspect of the second
molar. Additional sutures are placed posteriorly from that
position and anteriorly through the papilla on the mesial
side of the second molar. Usually three or four sutures are
necessary to close an envelope incision. If a releasing incision was used, attention must be directed to closing that
portion of the incision as well.
PERIOPERATIVE PATIENT MANAGEMENT
FIG. 9-50 Delivery of impacted maxillary third molar. A, Once soft
tissue has been reflected, small amount of buccal bone is removed
with bur or hand chisel. B, Tooth is then delivered by small
straight elevator, with rotational and lever types of motion. Tooth
is delivered in distobuccal and occlusal direction.
which distobuccally luxates the tooth. Some surgeons
prefer angled elevators, such as the Potts or Miller elevators, which aid in gaining access to the impacted tooth.
The elevator tip is inserted into the area at the mesial
cervical line, and force is applied to displace the tooth in
the distobuccal direction (Fig. 9-50). The surgeon
should be cautious about applying excessive pressure
anteriorly to avoid damage to the root of the maxillary
second molar. In addition, as pressure is applied to
displace the tooth posteriorly, the surgeon should have
a finger on the tuberosity of the maxilla (especially if
the impaction is mesioangular) so that if a fracture does
occur, steps can be taken to salvage the tuberosity of the
maxilla.
Step 5: Debridement of wound and wound closure. Once
the impacted tooth is removed from the alveolar process,
the surgeon must direct attention to debriding the
wound of all particulate bone chips and debris. The surgeon should irrigate the wound with sterile saline, taking
special care to irrigate thoroughly under the reflected
soft tissue flap. The periapical curette is used to
mechanically debride both the superior aspect of the
socket and the inferior edge of the reflected soft tissue
to remove any particulate material that might have
accumulated during surgery. The bone file is used to
smooth any sharp, rough edges of bone. A mosquito
hemostat can be used to remove any remnants of the
dental follicle. Once the follicle is grasped, it is lifted
with a slow, steady pressure and
The removal of impacted third molars is a surgical procedure that is associated with a large amount of patient
anxiety. In addition, this surgical procedure can involve
unpleasant noises and sensations. As a result, surgeons
who routinely perform surgical removal of impacted
third molars commonly recommend to their patients
some type of profound anxiety control such as a general
anesthetic or deep intravenous (IV) sedation.
The choice of technique is based on the surgeon's preference. However, the goals are to achieve a level of
patient comfort that allows the surgeon to work efficiently and that limits the patient's experience to the
minimal number of unpleasant effects.
Whether a deep IV sedative or a light general anesthetic
is used, most surgeons intend their patients to have little, if
any, unpleasant memory of the surgical experience.
In addition to the increased need for anxiety control,
a variety of medications are required to control the sequelae of third molar extraction surgery. The use of longacting local anesthetics should be considered in the
mandible. They will provide the patient with a pain-free
period of 4 to 6 hours during which prescriptions can be
filled and analgesics taken. The surgeon should consider
writing a prescription for a potent oral analgesic for every
patient who undergoes surgical removal of an impacted
third molar. Enough tablets should be prescribed to last
for 3 or 4 days. Combinations of codeine or codeine congeners with aspirin or acetaminophen are commonly
used. Nonsteroidal antiinflammatory drugs (NSAlDs)
may be of some value for certain patients.
To minimize the swelling common after the surgical
removal of impacted third molars, some surgeons prefer
to give parenteral steroids. IV administration of a modest
amount of a glucocorticoid steroid provides sufficient
antiinfiammatory activity to give relief to swelling.
Although many different regimens and protocols for
steroids exist, a relatively common one is the single
administration of 8 mg of dexamethasone before surgery.
This is a relatively long-acting steroid, and its efficacy in
controlling third molar postsurgical swelling is documented. Although steroids given in this manner have few
side effects or contraindications, the general philosophy
of weighing the risks and benefits of drug administration
must be carefully followed before the decision is made to
give these drugs routinely.
Many surgeons recommend the use of ice packs on the
face to help prevent postoperative swelling. Although it is
unlikely that the ice has much effect on preventing
swelling, patients frequently report that the ice made
them feel more comfortable. Something cool applied to
the face often makes patients more comfortable. It also
provides them the opportunity to participate in their
postoperative care, which is important for many patients.
The intraoral use of ice may have additional benefit. Gently sucking on small pieces of ice or even on commercial
Popsicles may be of some value in helping patients feel
more comfortable, although any measurable decrease in
swelling in patients who use this technique is unlikely.
Another medication that is sometimes used is an antibiotic. If a patient has had a preexisting pericoronitis, it is
common to prescribe antibiotics for a few days after surgery. However, if the patient is healthy and the clinician
finds no systemic indication for antibiotics or a preexisting
local infection, antibiotics are usually not indicated.
The normal postoperative experience of a patient after
surgical removal of an impacted third molar is more
involved than after a routine extraction. The patient can
expect a modest amount of swelling in the area of the surgery for 3 to 4 days, with the swelling completely dissipating by about 5 to 7 days. A modest amount of discomfort usually follows the procedure. This discomfort
can be effectively controlled with potent oral analgesics.
Patients usually require analgesics for 2 or 3 days on a
routine basis and intermittently for several more days.
The patient may have some mild soreness in the region
for 2 to 3 weeks after the surgery.
Patients who have had mandibular third molars surgically removed frequently have mild-to-moderate trismus.
This inability to open the mouth interferes with the
patient's normal oral hygiene and eating habits. Patients
should be warned that they will be unable to open their
mouths normally after surgery. The trismus gradually
resolves, and the ability to open the mouth should return
to normal by 10 to 14 days after surgery.
All of the sequelae of the surgical removal of impacted
teeth are of less intensity in the young, healthy patient
and of far greater intensity in the older, more debilitated
patient. Even healthy adult patients between the ages of
35 to 40 years have a significantly more difficult time
after the extraction of impacted third molars than do
healthy 17-year-old patients.
See Chapter 10 for a more detailed description of postoperative care.
REFERENCES
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the basis of radiographic features, Br ] Oral Maxillofac Surg
29:259, 1991.
2. Venta I et al: Clinical follow-up study of third molar erup
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72:150, 1991.
3. Bruce RA, Frederickson GC, Small GS: Age of patients and
morbidity associated with mandibular third molar surgery, J
Am Dent Assoc 101:240, 1980.
4. Marmary J et al: Alveolar bone repair following extraction of
impacted mandibular third molars, Oral Surg Oral Med Oral
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5. Meister F Jr et al: Periodontal assessment following surgical
removal of mandibular third molars, Gen Dentistry 14:120,
1986.
6. Osborne WH, Snyder AJ, Tempel TR: Attachment levels and
crevicular depths at the distal aspect of mandibular second
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7. Lysell L, Rohlin M: A study of indications used for removal
of the mandibular third molar, Int J Oral Maxillofac Surg
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pericoronitis and the position of the mandibular third
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10. Stanley HR et al: Pathological sequelae of "neglected"
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12. Richardson ME: The role of the third molar in the cause of
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13. Kugelberg CF: Periodontal healing two and four years after
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14. Kugelberg CF et al: The influence of anatomical, pathophysiological and other factors on periodontal healing after impact
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